1. Field of the Invention
Embodiments of the present invention relate to an image encoding/decoding apparatus and method, and more particularly, to an image encoding/decoding apparatus and method, which may provide a method for predicting an arbitrary motion vector of a current block within an image.
2. Description of the Related Art
Recently, along with a significant increase in high quality digital video contents, demands for transmission of the high quality digital video contents and for play services have increased.
To meet the demands, technologies that may encode and compress video contents with a high bit rate and a high resolution may become very important.
H.264/AVC, a video coding standard, may use, as a prediction signal, a motion vector (MV) of an adjacent block having been previously encoded to encode a motion vector in a B (Bi-predictive) block having two motion vectors. Hereinafter, the two motion vectors may be referred to as a first motion vector and a second motion vector, respectively.
FIG. 1 is a diagram illustrating a block predicted by a conventional video encoding scheme.
Referring to FIG. 1, a current block 10 to be encoded and a plurality of adjacent blocks 11 to 14 neighboring the current block 10 are illustrated. In this example, the adjacent blocks may be reconstructed blocks neighboring the current block, and an encoder and a decoder may include vector information associated with motion vectors with respect to the adjacent blocks. The current block may be a target block to be currently encoded.
In this instance, the plurality of adjacent blocks 11 to 14 may have at least one of vector information such as an actual motion vector, a predicted motion vector, and a differential signal between the actual motion vector and the predicted motion vector. Specifically, the adjacent block A 11 has a first motion vector, that is, MV_A_1 and a second motion vector, that is, MV_A_2, and the adjacent block B 13 has a first motion vector, that is, MV_B_1 and a second motion vector, that is, MV_B_2. Similarly, the adjacent block C 14 has a first motion vector, that is, MV_C_1 and a second motion vector, that is, MV_C_2, and the adjacent block D 12 has a first motion vector, that is, MV_D_1 and a second motion vector, that is, MV_D_2.
According to a conventional prediction method for a first motion vector of the current block 10, when the adjacent blocks use the same reference picture list and the same reference picture index as the current block, a median prediction may be realized by the following Equation.PMV1=median{MV_A_1,MV_B_1,MV_C_1}  [Equation]
Consequently, the first motion vector of the current block 10 may be calculated by the respective first motion vectors (MV_A_1, MV_B_1, and MV_C_1) of the plurality of adjacent blocks 11 to 14.
Also, a conventional prediction method for a second motion vector of the current block 10 may be realized by the following Equation.PMV2=median{MV_A_2,MV_B_2,MV_C_2}  [Equation]
Consequently, the second motion vector of the current block 10 may be calculated by the respective second motion vectors (MV_A_2, MV_B_2, and MV_C_2) of the plurality of adjacent blocks 11 to 14.
In this manner, the conventional video encoding method may use only a vector corresponding to a currently predicted motion vector from among a plurality of motion vectors of the adjacent blocks, and may fail to consider correlation and similarity among the plurality of motion vectors.